Modern pacemakers monitor the activity of a heart and provide a stimulation pulse in the absence of normal heart activity. Such devices are relatively small, light-weight and implantable. In order to sense and stimulate the heart, however, such pacemakers must be used with a pacemaker lead—an electrical conductor that carries electrical signals between the heart and the pacemaker. Advantageously, the pacemaker lead can be inserted into the heart transvenously through a relatively simple and well-known surgical procedure. Disadvantageously, one end of the lead (designated herein as the “connecting end”) must be electrically and mechanically secured to the pacemaker in a way that provides for a long-term safe and secure, yet detachable, connection. Those skilled in the pacemaker art have long sought for a simple, yet reliable and safe, technique for making this detachable electrical and mechanical connection between the pacemaker device and the connecting end of the pacemaker lead.
In order to appreciate the advantages of the present invention, it will help first to have a basic understanding of the manner in which the mechanical and electrical connection functions are carried out in known pacemakers. The main components associated with the connection function of known pacemakers are shown in FIGS. 1 and 2. A pacemaker 10 electrically includes a battery 14 that powers electrical circuits 12. The pacemaker electrical circuits 12 and battery 14 are mechanically housed and hermetically sealed in a suitable housing 16. Typically, this housing 16 is shaped to include a flat side or platform 20 to which a suitable epoxy connector 22 can be bonded. At least one feedthrough terminal 18, in electrical contact with the electrical circuits 12, passes through the housing 16 and protrudes out from the platform 20. This feedthrough terminal 18 is electrically isolated from the housing 16. A platinum wire 24, or other suitable conductive element, connects the terminal 18 to a conductive connector block 26 that is fitted within the connector 22. A pacemaker lead 28, having a proximal electrode 30, connects to the pacemaker electrical circuits by inserting the proximal electrode 30 into a receiving channel 31 of the connector 22 until the electrode 30 is in contact with the connector block 24. A set screw 32 is then securely tightened using a torque wrench 34 to firmly hold the electrode 30 in both mechanical and electrical connection with the connector block 26. A septum (not shown) is typically placed over the set screw 32 in order to prevent body fluids from seeping through the set screw hole. Further, sealing ribs or ridges 36 on the connecting end of the pacemaker lead are designed to tightly engage the inside edges of the receiving channel 31 in order to prevent any body fluids from entering into the receiving channel 31 once the connecting end of the lead has been pushed into the connector 22.
Representative descriptions of many of the features and functions of prior art pacemaker connection systems may be found in U.S. Pat. Nos. 4,934,366 to Truex et al.; 5,383,914 to O'Phelan; Re. 31,990 to Sluetz et al.; and 6,755,694 to Ries et al. Traditionally, as observed in these patents, implantable medical devices have had all leads exiting from the same side of the device. With the advent of HF (heart failure) and other devices with many bores, the lead insertion zone on the header has become cluttered and challenging to determine which lead belongs in which bore. Traditional configurations have all the setscrews and septums grouped in generally the same location, causing the header to have a larger and more intrusive volume. On some medical devices, the high voltage setscrew block (or spring contact) is located far from the feedthrough, necessarily resulting in a long wire with increased resistance that can compromise the lifespan and performance of the medical device.
To counteract this drawback of traditional designs, a multi-directional bore configuration header is hereby proposed which includes two or more lead bores that are open to and align in two or more unique directions, that is, the leads are plugged into the device from two or more unique directions. Other benefits of the multi-directional bore configuration header is to minimize header size, simplify and improve reliability of wire routing, and establish a unique and easily distinguishable bore configuration. The size of a header that houses multiple bores may be significantly reduced by aligning the contained bores in two or more unique directions. This is accomplished by spacing out the setscrew blocks and septums. If the device allows, the bores can be located tip-to-tip reducing vertical height and volume. The internal routing of wires contained within a multi-bore header can be simplified and made more reliable by aligning the bores in multiple directions. A wire's resistance is a function of its length. By shortening the wires, the resistance is reduced thus minimizing battery drain and increasing the life of the battery and device. By aligning the bores in multiple directions, a unique and easily distinguishable bore configuration is established. This simplifies the operating room procedure of determining which bore houses which lead; for example if all IS-4 leads are on the left and all IS-1 leads are on the right. For explanation, IS-4 is a proposed international standard (officially “Active implantable medical devices—four-pole connector system for implantable cardiac rhythm management devices”) calls for seals to be placed in the connector cavity and not on the lead connector. The older IS-1 international standard calls for sealing rings on the lead itself, a terminal pin electrode, and a single ring electrode proximally spaced from the terminal pin electrode.
In one known instance, a cardiac monitor includes telemetry to permit cardiac data to be interrogated externally of a patient for obtaining the generated cardiac data indicative of arrhythmic and ischemic episodes. In one embodiment of the monitor, the connector receptacles are disposed in opposing relation permitting conduits to directly extend from the header in opposed relation. However, there is no mention of the particular construction enabling electrical connection to the electronic circuitry within the enclosure for the monitor.
In another known instance, a multi-output connector is disclosed for an implantable stimulator with dual output blocks formed on opposite sides of the device. Again, however, there is no mention of the particular construction enabling electrical connection to the electronic circuitry within the enclosure for the device.
It was in light of the foregoing that the present invention was conceived and has now been reduced to practice.